/*
 * Copyright 2007 Rob Nielsen
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * 	http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.googlecode.proxymatic.core.handlers.method;

import com.googlecode.proxymatic.core.AbstractMethodHandler;
import com.googlecode.proxymatic.core.BuildtimeContext;
import com.googlecode.proxymatic.core.MethodInvoker;
import com.googlecode.proxymatic.core.ProxyBuilder;
import com.googlecode.proxymatic.core.RuntimeContext;

import java.lang.reflect.Method;

/**
 * This method handler is used to return an implementation object.  It will be activated if the return type of the
 * method is equal to or a superclass of the return type (excluding Object as this would match every method returning
 * java.lang.Object).  This handler is useful in wrapping proxies where you sometimes need to get out the real object.
 */
public class ImplementationObjectMethodHandler extends AbstractMethodHandler {

    public MethodInvoker getInvoker(Method method, BuildtimeContext context, ProxyBuilder proxyBuilder) {
        if (!context.isImplementationAvailableAtRuntime()
                || method.getReturnType().equals(Object.class)
                || method.getParameterTypes().length > 0) {
            return NOT_HANDLED;
        }
        int index = 0;
        for (Class implementationClass : context.getImplementationClasses()) {
            if (method.getReturnType().isAssignableFrom(implementationClass)) {
                final int implementationObjectIndex = index;
                return new MethodInvoker() {
                    public Object invoke(Method method, Object[] parameters, RuntimeContext context) throws Throwable {
                        return context.getImplementationObject(implementationObjectIndex);
                    }

                    public Class[] getExceptionTypes() {
                        return NO_DECLARED_EXCEPTIONS;
                    }
                };
            }
            index++;
        }
        return NOT_HANDLED;
    }
}
